1. Field of the Invention
The present invention relates to a safety circuit for the fuel supply system of a motor vehicle.
2. Description of the Prior Art
In a fuel tank assembly wherein fuel vaporized in a fuel tank is introduced and collected into a canister or an intake system through an air breather pipe, there has already been developed and laid open in the official gazette of Japanese Utility Model Registration Application Laid-open No. 98023/1989 a system in which the air breather pipe is furnished with a solenoid valve, and in which, when a liquid level switch provided in the fuel tank detects the arrival of poured fuel at a prescribed level, the solenoid valve is closed, while at the same time, an alarm lamp and a buzzer are actuated, thereby to prevent excessive fueling.
Heretofore, in fueling a fuel tank mounted on a vehicle at a gasoline station, it has been requested as mere guidance to stop the engine of the vehicle in consideration of safety. No problem occurs as long as the expedient is practised that, when the driver of the vehicle asks for the fueling at the gasoline station, he/she pulls a key plate out of an ignition key switch and delivers it to an employee at the gasoline station so as to open the flap of the fuel tank. In contrast, in a case where the driver delivers a spare key plate without extracting the key plate from the ignition key switch or where the flap of the fuel tank is opened by the manipulation of a remote-control opener switch having come into wide use in recent years, there is the problem that the fueling is possible even during the rotation of the engine including the starting mode thereof, so the safety of the fueling operation cannot be secured.